Treatment in an automatic clothes dryer has been shown to be an effective means for imparting desirable tactile properties to fabrics. For example, it has become common to soften fabrics in an automatic clothes dryer rather than during the rinse cycle of a laundering operation. See, for example, U.S. Pat. No. 3,441,692, Gaiser, issued May 6, 1969.
Fabric softness or conditioning is usually understood to be that quality of the treated fabric whereby its handle or texture is smooth, pliable and fluffy to the touch. Various chemical compounds have long been known to possess the ability to soften fabrics when applied to them during a laundering operation.
Fabric conditioning also connotes the absence of static "cling" in the fabrics, and the commonly used cationic fabric softeners provide both softening and antistatic benefits when applied to fabrics. Indeed, with fabrics such as nylon and polyester, the user is more able to perceive and appreciate an antistatic benefit than a true softening benefit.
Fatty alkyl cationic antistatic softening compounds and compositions designed for application to fabrics in an automatic dryer have been the subject of many innovations. See, for example, U.S. Pat. No. 3,634,947, Furgal, issued Jan. 18, 1972, and U.S. Pat. No. 3,686,025, Morton, issued Aug. 22, 1972. Other fatty materials have been suggested for use as dryer-added fabric softeners. See, for example, U.S. Pat. No. 3,676,199, Hewitt et al., issued July 11, 1972. Included among these prior softening compositions are various glycerides in combination with oil-soluble, lower-ethoxylated surfactants. Triglyceride fabric treating agents are disclosed in U.S. Pat. No. 3,785,973, Bernholz et al., issued Jan. 15, 1974.
The use of primary amines and the salts of such amines as fabric conditioning agents for use in the washing and rinsing cycles of an automatic washer, as well as the drying cycle of an automatic dryer has been disclosed. See, for example, U.S. Pat. No. 3,095,373, Blomfield, issued June 25, 1963; U.S. Pat. No. 3,442,692, Gaiser, issued May 6, 1969; and South African Pat. No. 69/3923. The use of primary amines in a dryer content, however, causes odor problems and paint softening. These problems are overcome with some salts, but not predictably so.
U.S. Pat. No. 4,077,891, Beimesch et al., issued Mar. 7, 1978, discloses the advantages of using the formic acid salt of a long-chain primary amine to impart a softening and antistatic effect to fabrics in an automatic dryer.
It has now been surprisingly discovered that certain imidazoline-anionic surfactant ion-pair complexes are fabric conditioning actives that can provide excellent static control and softness to fabrics in an automatic laundry dryer.
It is therefore an object of the present invention to provide superior static control and softness to fabrics treated with imidazoline-anionic surfactant ion-pair complexes in an automatic laundry dryer.
This and other objects are obtained herein, as will be seen from the following disclosure.